Process

Abstract

There is provided a method for reducing the amount of silica in a desert sand of a type that also comprises calcium carbonate, iron oxide and alumina components, to thereby produce a cement raw material feedstock, the method comprising: imparting a net negative electrical charge to a silica component and a net positive electrical charge to a calcium carbonate component of the desert sand through interparticle friction by a triboelectrostatic mechanism; and applying an electric field to the charged components of the desert sand by a triboelectrostatic mechanism; such that the negatively charged silica component is separated from a remainder of the components of the desert sand to thereby produce the cement raw material feedstock.

1 . A method for reducing the amount of silica in a desert sand of a type that also comprises calcium carbonate, iron oxide and alumina components, to thereby produce a cement raw material feedstock, the method comprising:
 imparting a net negative electrical charge to a silica component and a net positive electrical charge to a calcium carbonate component of the desert sand through interparticle friction by a triboelectrostatic mechanism; and   applying an electric field to the charged components of the desert sand by a triboelectrostatic mechanism;   
       such that the negatively charged silica component is separated from a remainder of the components of the desert sand to thereby produce the cement raw material feedstock. 
     
     
         2 . A method according to  claim 1 , wherein the desert sand is a naturally occurring desert sand, such as a sand typically occurring in arid deserts having a Köppen climate classification of BWh. 
     
     
         3 . A method according to  claim 1 , wherein the imparting of the electrical charge by interparticle friction and the application of the electric field occurs concurrently in a conveying triboelectrostatic separation stage. 
     
     
         4 . A method according  claim 1 , wherein the triboelectrostatic mechanism by which the electric field is applied to the charged components of the desert sand, comprises an active positive electrode and an active negative electrode. 
     
     
         5 . A method according to  claim 3 , wherein the conveying triboelectrostatic separation stage comprises a belt-type triboelectrostatic separation stage. 
     
     
         6 . A method according to  claim 3 , wherein the triboelectrostatic separation stage comprises a plurality of triboelectrostatic separation stages. 
     
     
         7 . A method according to  claim 6 , wherein the plurality of triboelectrostatic separation stages are arranged in series and/or in parallel. 
     
     
         8 . A method according to  claim 4 , wherein the voltage applied to each electrode to produce the electric field does not exceed 10 kV. 
     
     
         9 . A method according to  claim 1 , the method further comprising a comminution step. 
     
     
         10 . A method according to  claim 9 , wherein the comminution step is carried out prior to reducing the amount of silica in the desert sand. 
     
     
         11 . A method according to  claim 1 , wherein the method further comprises imparting additional electrical charge to the silica component and to the calcium carbonate component by passing the desert sand through a fluidized bed reactor, a cyclone apparatus or another apparatus for generating interparticle friction within the desert sand. 
     
     
         12 . A method according to  claim 1 , wherein the desert sand comprises iron oxide in an amount, by weight, greater than about 0.5%. 
     
     
         13 . A method according to  claim 1 , wherein the desert sand comprises alumina in an amount, by weight, greater than about 1%. 
     
     
         14 . A method according to  claim 1 , wherein one or more parameters relating to the composition of the desert sand and/or the cement raw material feedstock is/are measured, with the measurement of the one or more parameters used to determine a set of optimum parameters for the separation of the silica component from the remainder of the components of the desert sand. 
     
     
         15 . A method according to  claim 14 , wherein the one or more parameters relates to the silica component of the desert sand and/or the cement raw material feedstock. 
     
     
         16 . (canceled) 
     
     
         17 . A method according to  claim 14 , wherein the one or more parameters is measured by X-ray fluorescence or X-ray diffraction. 
     
     
         18 . A cement raw material feedstock comprising calcium carbonate, iron oxide and alumina components, produced by the method as set forth in  claim 1 . 
     
     
         19 . Use of a desert sand of a type that also comprises calcium carbonate, iron oxide and alumina components for the production of a cement raw material feedstock, wherein, prior to producing the cement raw material feedstock, the amount of silica in the desert sand is reduced according to the method of  claim 1 .